1. Field of the Invention
The invention relates to a light emitting device, more particularly to a light emitting diode.
2. Description of the Related Art
As shown in FIG. 1, a conventional light emitting diode includes a base 11 formed with a recessed portion 111, a light emitting chip 12 provided on a bottom wall surface of the recessed portion 111 and having a top chip surface and a peripheral chip surface, and a fluorescent layer 13 filled in the recessed portion 111 so as to cover the top chip surface and the peripheral chip surface of the light emitting chip 12. The fluorescent layer 13 contains phosphor particles 131 for converting a part of blue light emitted from the light emitting chip 12 into yellow light, so that the mix of blue and yellow light results in white light. However, since light (L2) emitted from the peripheral chip surface travels in the fluorescent layer 13 longer than light (L1) emitted from the top chip surface, the light (L2) is more likely to be converted into yellow light than the light (L1), thereby making the light obtained from the conventional light emitting diode yellowwish.
U.S. Pat. No. 5,959,316 discloses another conventional light emitting diode (see FIG. 2) that eliminates the aforementioned drawback by first covering the top chip surface and the peripheral chip surface of the light emitting chip 12 with a transparent spacer 14, and then disposing the fluorescent layer 13 to cover the transparent spacer 14. Since the fluorescent layer 13 has a uniform thickness, light emitted from different parts of the light emitting chip will be eventually converted to obtain output light that is less yellowish.
Moreover, U.S. Pat. Nos. 6,576,488, 6,417,019 and 6,650,044 disclose methods such as electrophoresis and stenciling to manufacture still another conventional light emitting diode (see FIG. 3) including the fluorescent layer 13 that has a uniform thickness and that is disposed to directly cover the top chip surface and the peripheral chip surface of the light emitting chip 12. However, these methods can only be applied to the light emitting chip 12 that is mounted to the base 11 via chip bonding process (see FIG. 4) rather than wire bonding process. Furthermore, these methods lead to higher manufacturing costs, thereby impeding the popularity of the conventional light emitting diode.